Electric heating unit



C, C. ABBOTT.

ELECTRIC HEATING UNIT.

,APPLICATION FILED DEC. 17. 1920.

Patented Oct. 18,1921.

' Inventor Charles C. Abbott.

His Attorney CHARLES C. ABBOTT, OF IITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELEC- TRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC HEATING UNrr.

Specification of Letters Patent.

Patented Oct. 18, 1921.

Application filed December 17, 1920. Serial No. 431,467.

To all whom it may concern:-

Be it known that I, CHARLES C. Anno'rr, a citizen of the United States, residing at Pittsfield, county of Berkshire, State of Massachusetts, have invented certain new and useful Improvements in Electric Heating Units, of which the following is a specification.

My invention relates to electric heatlng units and has for its object the provision of.

simple, compact and reliable means for generating heat by the use of an electric current.

More specifically my invention relates to an electric heating unit of the resistance type. It is often advantageous in the heating of various types of machinery to use a small compact heating unit which is designed to operate on a low voltage grounded circuit. My invention is particularly adapted for use in installations of this character, although it has other applications.

Other objects and features of my invention will appear in the course of the following specification in which I'" have shown my invention embodied in concrete form for the purpose of illustration.

Referring to .the drawing, Figure 1 shows a perspective view of a heating unit constructed in accordance with my invention; Fig. 2 is a vertical enlarged section of the device shown in Fig. 1, while Fig. 3 is a plan view showing various'parts in dotted lines.

Referring to Fig- 2 of the drawing, a cy lindrically shaped insulator or core 12, constructed of lava or other suitable material, is supported in a central position in casing 10 by means of a stud 14 which cooperates with a hole in the insulator. Stud 14 is rigidly fixed to the casing in any suitable manner.

The insulator 12 has a peripheral groove 26 in which a helical resistance element 13 is supported. T .One end of the resistance element extends through the casing at point 21 where it is brazed to the casing in a slot 27, making a ground connection. The other end of the resistance element is brazed in a slot 22 in the end 0 terminal post 18- Terminal, post 18 is s urely anchored in the casing by means of a metallic disk 15 having a threaded'hole into which the terminal post isscrewed by means of cooperating threads on theend thereof and securely brazed. The

terminal post extends a short distance through dlsk 15, to provide for which the insulator 12 is cut away as shown at 25. DlSk 15 is insulated from stud 14 by washer 17 made of a suitable insulating material and from casing 10 by insulating washer 16. Insulating washer 20 is seated in a depres- S1011 2 0 in the casing and holds the terminal post in central position in hole 19 in the casing through which the terminal post extends. The terminal post is thereby insulated from the casing. A suitable connecting terminal 24 is attached at the outer end of the terminal post.

After the various parts mentioned above have been assembled, as shown in the drawing,-the casing is filled with a granular insulating material 23, such as magnesium oxid. The casing is then vibrated to shake the insulating material together after which the cover 11, consisting of a metallic disk havlng a sloping edge, is put in place and the unit subjected to heavy pressure whereby it is compressed to a solid compact mass. The upper edge of the casing is then compressed to a slightly smaller diameter onto the sloping edge of the top 11 thus firmly sealing the top in place.

In a heating unit which is constructed as previously described the granular insulat ing material will be packed within the casing around the insulator, and around the resistance element between the turns thereof.

lVhile I have here shown an embodiment of my invention which is, at present, the best means known to me, I would have it understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art without departing from the sprit of my invention, the scope of which is set forth in the annexed claims.

WVhat I claim as new and desire to secure by Letters Patent of the United States, is,

1. An electric heating unit comprising-a casing, a core of insulating material in said casing having a groove, a resistance element wound in helical form and wound in said groove, and granular insulating ma terial packed within the casing around the core and the resistance element.

2. An electric heating unit comprising a casing, a core of insulating material in said casing having a groove, a helical resistance element supported on said core with its axis in said groove, and granular insulating material packed Within the casing around the core and the resistance element.

3. An electric heating unit,,comprising ametallic casing, a cylindric core of insulating material in said casing having a peripheral groove, a helical resistance element supported on said core with its axis in said groove, and granular insulating material packed Within said casing around the core and the resistance element.

4. An electric heating unit comprising a metallic casing, a core of insulating material in said casing having a groove, a helical resistance element supported on said core with its aXiS in said groove having one end connected to the casing, a terminal insulated from the casing for the other end of the resistance element, and granular insulating material packed within the casing around the core and the resistance element.

5. An electric heating unit comprising a metallic casing, a core of insulating material in said casing having a groove, a helical re sistance element supported on said core with its axis in' said groove having one end connected to the casing, a terminal supported within the casing and insulated therefrom for the other end of said resistance element, and granular insulating material packed Within the casing around the core and the resistance element.

6-. An electric heating unit comprising a metallic casing, a core of insulating material supported in said casing and having a groove, a helical resistance element on said core with its axis\in said groove having one end connected to the casing, a terminal extending Without the casing for the other end of the resistance element, a metallic disk in the casing for supporting the terminal, means for insulating said disk and terminal from the casing,-and granular insulating material packed Wtihin the casing around the core and the resistance element.

7. An electric heating unit comprising a metallic casing of heat conducting material, a cylindric insulator having a peripheral groove in said casing, a. helical resistance element supported on said insulator with its axis in said groove having one end connected to the casing, a terminal insulated from the casing for the other end of the resistance element, and granular insulating material packed within the casing around the insulator and the resistance element.

8. An electric heating unit comprising a metallic casing of heat conducting material, a cylindric insulator having a peripheral groove supported centrally in said casing, a helical resistance element supported on said insulator with its axis in said groove having one end connected to'the casing, a terminal extending Without the casing for the other end of the resistance element, a metallic disk in the casing for supporting said terminal, means for insulating the disk and terminal from the casing, and granular insulating material packed within the casing around the insulator and resistance element.

In witness whereof, I have hereunto set my hand this 13th day of December, 1920.

CHARLES C. ABBOTT. 

